Today, new types of communication networks are being developed for the transfer of information in circuit-switched channels of time division multiplexed networks. In such a network, a recurrent frame of the network is divided into time slots, and said circuit-switched channels are established to comprise respective one or more time slots of said recurrent frame. Hence, each channel will be allocated a respective set of one or more time slots within said recurring frame, thereby gaining exclusive write access to said respective set of time slots.
One example of such a network is the so-called DTM network (DTM—Dynamic Synchronous Transfer Mode). DTM is a broadband network architecture (see e.g. Christer Bohm, Per Lindgren, Lars Ramfelt, and Peter Sjödin, The DTM Gigabit Network, Journal of High Speed Networks, 3(2), 109-126, 1994, and Lars Gauffin, Lars Håkansson, and Bjorn Pehrson, Multi-gigabit networking based on DTM, Computer Networks and ISDN Systems, 24(2), 119-139, April 1992).
Prior art describes rules for deciding, at a node of such a network, when the node shall give away write access to time slots to other nodes, i.e. to deallocate time slots in the favor of other nodes. For example, as disclosed in WO 97/36402, a node will give away time slots if it has any free slots available, i.e. slots not allocated to any one of the end users served by said node. However, in many cases there will be a need for more flexible rules, providing more options in the control of allocation and deallocation of time slots. Also, in this prior art, a resource shortage problem will occur if there are no free slots available in the frame of interest to respond to a request for additional slots transfer capacity.